The region of electromagnetic waves lying in the giga-terahertz (THz) frequency range has recently become of increasing interest in various fields of science and technology. In part, such interest is caused by the upcoming need for higher frequency computer communication channels and systems. In addition, large toxic molecules of biological and chemical agents have resonant absorption lines in the THz region, thereby enabling, for example, tomography of different human tissues. Also detection of certain (chemical) weapons and explosives could be accomplished. Other potential applications can encompass detection of structural and other defects in materials, food inspection, and investigation of astronomical objects.